Sr、Cr掺杂NaCo_2O_4热电材料的制备及电性能

Preparation and Electric Properties of Sr-doped and Cr-doped NaCo_2O_4 Thermoelectric Materials

NaCo2O4具有良好的导电性能,是一种较有发展前景的热电材料。掺杂法通常被用来改变材料的物理化学性能。文章采用自助熔剂法制备Na位掺杂Sr和Co位掺杂Cr的NaCo2O4热电材料。通过XRD物相组成分析和电性能的测试,研究不同掺杂元素和不同掺杂量对NaCo2O4电性能的影响。试验结果表明,掺杂Sr和Cr均可提高材料的Seebeck系数,当两种掺杂元素的掺杂量为0.3时,其Seebeck系数在823 K时达到最大值,分别为180μVK-1和185μVK-1。虽然掺杂Sr和Cr均降低了NaCo2O4的电导率,但是Sr掺杂量为0.1时,由于Seebeck系数增大的贡献大于电导率减小的作用,功率因子有所提高,在823 K时达到最大值870μWm-1K-2,说明通过调控Sr量可以有效提高NaCo2O4的热电性能。

NaCo2O4 is a potential thermoelectric material due to its good electric properties. Doping can affect the physical and chemical properties of materials. In this paper, NaCo2O4 thermoelectric materials with Na-site doping by Sr and Co-site doping by Cr are prepared by self-flux method. The effect of two doping elements and their amounts on the electric properties of NaCo2O4 are investigated by XRD phase composition analyzing and electric properties measurements of the samples. As a result, both Sr and Cr can increase Seebeck coefficients of the materials. When doping amount of each element reaches at 0.3, the Seebeck coefficients are to a maximum value of 180 μVK-1for Sr and 185 μVK-1for Cr at 823 K, respectively. When Sr doping amount is x=0.1, the increase of the Seebeck coefficient is greater than the decrease of electric conductivity, so as to the power factor of NaCo2O4increase（the maximum value is 870 μWm-1K-2at 823 K） although their electric conductivities decrease, indicating the thermoelectric properties of NaCo2O4 can be improved effectively by regulating the amount of Sr.